Adds a didReceiveInputEvent api to the blink scheduler

Source/platform/scheduler/Scheduler.cpp

Index: Source/platform/scheduler/Scheduler.cpp
diff --git a/Source/platform/scheduler/Scheduler.cpp b/Source/platform/scheduler/Scheduler.cpp
index eb6c698604630c429e1374f82446497987a24b74..2bc137db631436e2baf9dc3e6a7cca1b87c7e05d 100644
--- a/Source/platform/scheduler/Scheduler.cpp
+++ b/Source/platform/scheduler/Scheduler.cpp
@@ -163,6 +163,11 @@ void Scheduler::postInputTask(const TraceLocation& location, const Task& task)
     TRACE_COUNTER1(TRACE_DISABLED_BY_DEFAULT("blink.scheduler"), "PendingHighPriorityTasks", m_highPriorityTaskCount);
 }
 
+void Scheduler::didReceiveInputEvent()
+{
+    enterSchedulerPolicy(CompositorPriority);
+}
+
 void Scheduler::postCompositorTask(const TraceLocation& location, const Task& task)
 {
     Locker<Mutex> lock(m_pendingTasksMutex);